Thread-cutting mechanism



March 22,192.7.

S. W. ELSTONE THREAD CUTTING MECHANISM Filed March 6. 1925 2 Sheets--SheP/rl 1 W IX mv wN.

w uw m. QN

March 22, 1927; v 1,622,190 n S. W. ELSTONE THREAD CUTTING MECHANISM i Filed March e. 1925 2 sheets-sheet 2 j @Hoz man! Patented Mar. 22, 1927.

` 1,622,1smff UNIT ED= SITA-T STANLEKWL ELSTITQCLW.i3,;QElWALKEaffitta caranto, cnnanaassrenoa, 'rov HURQN ivraItUrAorUnIn-eco., yor Darsena monteert, ooaronlirron or MionrGAN.

THREAD-CUTTING MECHANSM.

Application led'March 6, 1925'.A Serial No. 13,5332

This invention relates tothread cutting machinery and more particularly to amechanism which may be readily installed upoir any ordinary milling-machine and employed in cuttingfthreads iii-blanks, and while the mechanism is designed primarily for employment in cutting threads in washout 'andisimilar plugs for steam boilers, tanks,` etc.7

it may be employed in cutting threads inv other types offblanks. Likewise, while the mechanism is designedspecically for the purpose of cutting threads oi the square type, it may be employed infcutting other ty esci-threads.y

y eretofore considerable diiiiculty has been experienced in economically'threading plugs ofthe type vreferred 'to above, where the threads are-required to be of the square typeandthe threading operation. has consumed considerable time and 'difficulty has been experienced in.l performing the ywork accurately-l and Without Therefore; it -is'one ofthe important objects ofthepresent invention to provide a thread cutting mechanism by the use or' which lplug'blanks may be rapidly4 and accurately threaded withoutv likelihood `of vany defects in the work would result in waste of matef rialfas well as time and labor.

Heretofore, it has been customary `to form threads' ofthe square type by thefuse of lathesemploying cutting bits, but as stated1 above,H the. threading operation cannot bewastey oi material-.-

- tion indicated by the ar'rows.= y

trating the mechanism embodying the inven tion installed-in connection with a milling*- machine..

-iligure-v 2 vis avertical front to rear sec tionalaview taken'substantiallyy on the line out.:

22 yof `Figure 1, looking inV the direction.y indicatedv bythe arrows.

Figure 3 1s 1asimilarfview takenV on the.

lineS-S of liigurel,v looking. in-r the direc.-

imeral thei-teetlroi' Vthe-several series-being arranged helically abouti the; body, off'SOz;

the cutter-head and lthe Vteeth beingfvot-a rectangular contour and of-fdimensionsvtor'r carried out rapidly enoughto permit-of'- quantityproduction at a low--costand,there fore, it'fisanother important'objectoi the invention toprovide athread cutting-mechani-siniby theemploymentof which a ,re-y

quired number of threads may be'` simultaneously cut 'and` the cutting `operation performed expeditiouslyand atffthe same time more accurately' than-has heretofore been possibie..

Another object of the `inventionis'to prothe',worlcesupportwill be so -fed in conso-- cut threadsin the blanks ofthe-correspond` ing conto-ur. Iii-accordance with.thefinven` tion, the! teethi of eachV seriesareof ay num-.i .85# ber corresponding-to the number of threads.; to bel out in the Abla-inks and the purpose ot thisr-proportioningof the number of tee-th willipresently be made; clear.- f Y Fixed upon the vfbed 2 is a bedplate 7 pro 90M vided at-on'enend with an upstanding head 48 having-an opening Qthereiniin which is" removably'securedyas for example, by a setiscrew 10,*` a bushing-11, the bio-re oifwhich"k is formed with-threads V12.vr The numeraliii- 13 indicates a chuckl spindlewhich; for a portion of its length-is formedw-ith threads 14 to -t the threads 12,itrbeinguundeii y stood at this point' that .rotationr oiI the 'vid'e a threadcutting .mechanism-in whichy nance with; the operation of thecutterfhead" as to insure ofv accurate cutting of 'the threads;K the arrangement"bei-ngfsuch that the; mechanismH may be-readily and quickly adapted: for the 'cutting of: threads of various sizes. Y

In; the accompanying drawings; :i Figure -1 is -a .View Ypartly in' front elevation and partly in longitudinal section, illusspindle 13 will result Y in its being; fed 1001"- longitudinallyA through the said bushingf i 11.i The-numerall indicatesa block which x is slidablyy disposed upeni the bed f plate n 7 and guided o byv the v engagements of its base flangesl 1,6 withv spaced guides y17' `upon ,195"

13 is rotatably journaled in an opening 2O in the head stock 18 and the chuck is inW dicated by the numeral 21 and is provided with a center 22 and with spaced lugs 23 between which a portion of the work to be acted upon, as for example, the squared stud 24 of a washout plug blank 25, is disposed and clamped by means of a set screw 26 threaded through one of said lugs. The tail center is indicated by the numeral 2T and engages the other end of the blank25 and is slidably fitted through a bushing 28 in the tail stock 19` and has a yoke 29 straddling the shank of an adjusting screw 30 adjustably threaded into the said. tail stock. At this point, it will be understood that when the spindle 13 is rotated and fed lon gitudinally, it will 'carry with it the block 15 and the work supported between the chuck 21 and thetail center 27, the work being, atthe same time, rotated with the spindle. n v

lln order that' rotary motion may be im-V parted to the spindle 13 at a low rate of speed,'al gear 31 is fixed upon the end of the spindle and meshes with a pinion 32 upon a stub shaft 33 carried by the head stock 18, the said pinion rotating with a gear 34 liken wise mounted uponv the stub shaft and the said gear 34, in turn, meshing with a pinion 35 which is freely rotatably mounted upon a shaft 36, in turn mounted in suitable bearings` 37 beneath'the bed 2. Rotary motion is imparted to the shaft 36 through the medium of a shaft 38 which has universal connection,`as at 39, therewith.` the said sha-ft 38 being, in turn, driven from the drive shaft (not shown) of the milling machine. A clutch member 40 is fixed for rotation with the pinion 35, and a companion clutch member 41 is slidably mounted upon the outer end of the shaft 36 and held for rotation therewith by splines 42, the clutch member 41 being preferably provided with a knurled surface 43 whereby it may be readily manually shifted into and out of engagement with the clutch member 40, it being understood that while the shaft 36 rotates continuously, the pinion 35 and train of gearing driven therefrom will be idle until the clutch `membei` 41 is shifted into engagement with the clutch member 40, whereupon the gearing will beset in motion and rotary motion will be imparted to the spindle 13.

As `previously stated, in milling machines, the bed 2 is vertically movable and at the time Vof mounting the piece of work or blank n 25` the bed will be in lowered4 position.

After the blank has been properly mounted, n

therbed is elevated by the usual means pro vided for this purpose so as to bring the blank into position to be acted upon by the cutter head 4 and, at the same time, the

clutch member 41 is manually shifted into upon by the teeth 5 and threads will be cut therein, the speed of operation of the several parts being such that, inthe illustrated embodiment, four threads, will be cut in the blank 25 during one revolution of the spindle 13. lVhen the cutting operation' is completed, the clutch member 41 will be with-- drawn from engagement with the clutch member 40, the bed 2 lowered, `and a crank handle 44 which is associated with the spindle 13, will be manually operated to to its `normal or original position.

baekwardly rotate the spindleandrestore it As previously stated, onefofthe objects? of the invention is to provide a thread cut` ting mechanism in which the work support will be so fed in consonance with the operaa` tion of the cutter head as to `insure of accu-1V4 rate cutting of the threads and `in which the arrangement is Vsuch that the mechanism may be readily and quickly adapted forthe cutting of threads of various sizes.,` This is" accomplished by removing the cutter head and substituting one of another size and by looseningthe set screw 10 and bodily withdrawing thebushing 11andv the chuck spinxdle 13 which is carried thereby, and" sub-V stituting for these parts a bushing and chuck i spindle having threads Lof a'pitch andsize corresponding to the threads of the cutter head which is to be substituted for the one removed.

Having thus described the invention, what i I claim is:

A thread cutting" machine comprising a bed plate having an upstandinghead having any opening therein, a block slidably mounted upon the bed plate and havingu'pstanding v head and tail stocks, a work supporting ele ment carried by the tail stock, a spindle rotatablymounted in the head stock, a chuck carried by thesaid spindle for supporting the end of the work opposite the end which is engaged by the `said supporting `element stock. a bushing removably fitted in `the opening in the head'of the bed 'plate,.means removably securing the bushing inA place, the bushing lbeing interiorlyV threaded and the spindle having a threaded portion fittingV therein, a` gear iiredupon the spindle, and Y a drive gear `in mesh therewith and free from obstruction to lateral displacement and disengagement of the first mentioned gear therefrom when the securing means for the bushing is rendered inactive.

In testimony whereof I affix my signature.

STANLEY W. ELSTNE. r

and having a shoulder abutting `the head.115 

